Your stats aren't that far off, without checking my own wherever they are. However greyhounds are not getting a lot of the other illnesses that kill other breeds. So, the same amount of dogs die, just of cancer and not heart or kidney disease.
Jake limped like that and had a shoulder muscle injury. The vet who examined him wasn't sure, but the massage therapist I took him to pinpointed the exact spot of the injury and then the secondary pain sites. I treated with ice/heat, rest and Traumeel.